This invention relates generally to the field of signal transmission systems, and more particularly to a suspended transmission line with an embedded signal channeling device.
Microwave and radio frequency circuits are generally implemented by interconnecting amplifiers, antennas, transmitters, receivers, and other components by a series of transmission lines. The transmission lines propagate microwave and radio frequency energy between the components of the circuit.
Transmission lines are generally implemented as waveguide pipes, striplines, and/or coaxial cables. Waveguide pipes are often impractical, however, because of the difficulty of installation and the size and weight is excessive for many applications. Striplines and coaxial cables are more compact and easier to install, but use special materials and fabrication processes that lead to high transmission line cost.
Further adding to the expense of microwave and radio frequency circuits is the expense of implementing amplifiers, antennas, splitters, combiners, and other components within the circuit. Typically, each component is implemented in a specially fabricated mechanical housing such as an aluminum box having signal, digital, and power connectors. These mechanical housings must generally be designed, engineered, and machined with tight tolerances for microwave and other high frequency applications. In addition, drawing packages need to be generated and maintained for each application. Connectors must also be thermally matched to the mechanical housing.
The present invention provides a transmission line signal channeling device that substantially eliminates or reduces the problems and disadvantages associated with prior methods and systems. In particular, the signal channeling device is embedded into a suspended transmission line to divide or combine signals in cellular and other suitable frequency applications.
In accordance with one embodiment of the present invention, a suspended transmission line with an embedded signal channeling device includes a support layer and a conductor supported by the support layer between first and second plates each having a ground plane. The conductor includes a combined signal line and a plurality of discrete signal lines extending from the combined signal line. The discrete signal lines each transmit a portion of a signal transmitted on the combined signal line. A propagation structure is positioned between the first and second plates to substantially contain an electromagnetic field generated by the propagating signal.
More specifically, in accordance with a particular embodiment of the present invention, the discrete signal lines include first and second outside lines and a center line between the first and second outside lines. The center line includes a serpentine element to maintain substantially the same length, and thus phase, as the first and second outside lines.
Technical advantages of the present invention include providing a low cost and space efficient transmission system. In particular, a signal channeling device is embedded into a transmission line substantially without degradation in the height of the transverse cross-section of the line. As a result, the transmission line structure is self-contained and includes fewer parts. The cost of designing, engineering, constructing, and maintaining separate mechanical housings for a divider or a combiner is minimized.
In accordance with the present invention there is provided an improved signal channeling device for cellular and other suitable frequency applications. In particular, the signal channeling device is embedded within and integral with a suspended transmission line. The resulting channeling device provides good isolation and VSWR, as well as low insertion loss. In addition, the number of transmission line connectors for the channeling device is reduced. Thus, antenna and other systems using dividers and/or combiners may be constructed at relatively low cost.
Other technical advantages of the present invention will be readily apparent to one skilled in the art from the following figures, description, and claims.